Why does Backyard brains have clearer EOG
DashBarkHuss
Chicago
Why is Backyard brains EOG signal clearer than OpenBCI?
Here are some videos showing EOG on OpenBCI vs. Backyard brains.
Eye movement pattern tested:
Left, Right, Left, Right, two saccadic movements left, two saccadic movements tight, a quick Left + Right, several saccadic movements left, several saccadic movements right.
The signal is clear in Backyard brains: Left is a peak, right is a dip.
Backyard brains EOG Video
But in OpenBCI, the signal is hard to decipher.
OpenBCI EOG 200uv 5s scale Video
OpenBCI EOG 200uv scale Video
OpenBCI EOG 100uv scale Video
For OpenBCI, the resting states between eye movements have more noise. It's hard to see what happens to the signal when the eye moves left vs. right, but I can at least see the signal is affected by my eye movements.
What would cause this difference? Is it the hardware itself? What hardware specs could cause this difference? Is Backyard brains more suited for EOG? Why would that be? Or could some setting on OpenBCI make the signal on OpenBCI as clear a Backyard brains?
Note: I’m using an M1 mac with this USB adapter. I’ve heard there are issues with M1, but with this USB adapter, I no longer see a difference in signal between my M1 mac and my spouse’s intel chip mac.
Comments
EOG left / right movement is a LOW FREQUENCY signal. So if your filtering is removing low frequency components, then it will not look the same as the BB graph. Try turning off the GUI filtering entirely, then compare. Then turn on slowly just what you need.
I don't know a lot about filters. Backyard brains abstracted this away. I don't see a way to turn it off. Would I just set "notch" to "none"?
I got a better signal (Video) by making the "stop" and "start" larger. I don't understand filters, but I thought making the range larger would "include" most frequencies, thereby turning off the filter.
It also says this at the bottom of the GUI now. So maybe I just messed with the filter settings and now there are no filters somehow, unrelated to the stop and start range.
https://www.google.com/search?q=eog+filter+band
https://www.hindawi.com/journals/complexity/2018/4853741/
"Effect of EOG Signal Filtering on the Removal of Ocular Artifacts and EEG-Based Brain-Computer Interface: A Comprehensive Study"